Rapid, on-site production of peracetic acid (PAA) from safe, non-hazardous feedstocks is an enabling technology for facilities and applications where bulk storage and handling of hazardous materials is not permissible or where the consumption time exceeds the shelf life of bulk peracetic acid. Small quantity users of peracetic acid will especially benefit from on-site generation due to the impracticalities (hazardous and unstable) of distributing small quantities of peracetic acid.
Various methods for on-site peracetic acid production are known in the art. Disadvantages of such known methods are, among others, (1) the long reaction or cure times required to produce equilibrium concentrations of peracetic acid solutions; (2) costs of shipping, handling, and storage, (3) limited shelf life of concentrated acids, bases, and peroxides, which are all corrosives and hazardous materials; (4) cost of shipping large quantities of water containing merchant hydrogen peroxide; (5) the presence of stabilizers or contaminants originating from merchant hydrogen peroxide; (6) relatively low production rates or excessive equipment size and cost associated with direct electrochemical production of peracetic acid with gas diffusion electrode reactor technologies; (7) inability to recycle supporting electrolyte salts back into the production process. In addition, the practice of combining bulk chemical constituents obtained from merchant suppliers to produce non-equilibrium peroxycarboxylic acid solutions, including peracetic acid is incapable of producing the compositions provided herein. Processes and related devices provided herein eliminate these disadvantages and other disadvantages associated with shipping, storing and handling concentrated merchant peracetic acid.
U.S. Pat. Nos. 6,566,574, 6,723,890 and 7,271,137 all relate to compositions for neutralization or decontamination of chemical or biological toxins prepared by chemical mixing of various components including a reactive compound which can be hydrogen peroxide. U.S. Pat. No. 6,723,890 relates to an aqueous decontamination formulation comprising: a cationic surfactant; a cationic hydrotrope; certain reactive compounds (including hydrogen peroxide); a fatty alcohol having a concentration from greater than 1 wt. % to 2 wt %; and water. U.S. Pat. No. 7,271,137 relates to an aqueous decontamination formulation for use in disinfection and sterilization, consisting of (by weight percentage): 0.5-60% reactive compound selected from the group consisting of nucleophilic compounds and oxidizing compounds, which can be hydrogen peroxide; 1-10% water-soluble bleaching activator which can be monoacetin, diacetin, or triacetin, among other acetyl compounds, and; 3-30% of inorganic base which can comprise potassium acetate.
U.S. Pat. No. 7,235,252, Preto et al. relates to a system for rapid preparation, just before use, of organic peroxyacids, in a hydroalcoholic environment, by mixing separately stored first and second reactants, where the first reactant includes an acyl donating group and the second reactant is in the solid state and comprises a peroxide anion source, a biocidal agent including at least one linear or branched aliphatic and/or aromatic alcohol, and a stabilizing buffer component suitable for keeping the second reactant at a desired pH value.
U.S. Pat. No. 5,505,740 (Kong et. al) describes a method for in-situ formation of peroxyacid using peroxyacid precursor, a source of hydrogen peroxide and a source for delayed release of acid for a bleaching product (wash solution) and a method of removing soil from fabrics. In the method of Kong et al. the aqueous wash solution is initially raised to a relatively high pH level (e.g., 9.5) to enhance production of the peroxyacid in the aqueous solution, followed by lowering the pH of the aqueous solution by, for example, the delayed release of acid, to enhance bleach performance. The source of the delayed release of acid may be an acid of delayed solubility, an acid coated with a low solubility agent or an acid generating species, or an acid independent of the bleaching product employed.
U.S. Pat. No. 5,122,538, Lokkesmoe et al, (Ecolab) relates to a process to generate peroxy acid sanitizing and bleaching compositions at the point-of-use. The process comprising introducing hydrogen peroxide and a carboxylic acid into a reactor and contacting the hydrogen peroxide and carboxylic acid in the presence of a sulfonic acid resin and in the substantial absence of active metal ions to form an aqueous peroxy acid composition at concentrations up to 20 wt %.
British Pat. Pub. No. GB 1,456,592 relates to a bleaching composition having both encapsulated bleaching granules and agglomerated pH-adjustment granules acid. The bleaching granules comprise an organic peroxy acid compound stabilized by salt(s) of strong acids and water of hydration, encapsulated in a fatty alcohol coating. The pH-adjustment granules comprise a water-soluble alkaline buffer yielding pH 7-9 agglomerated with a suitable adhesive material to yield the desired solubility delay. Preferred peroxyacid compounds are diperisophthalic acid, diperazelaic acid, diperadipic acid, monoperoxyisophthalic acid, monosodium salt of diperoxyterephthalic acid, 4-chlorodiperoxyphthalic acid, p-nitroperoxy benzoic acid, and m-chloroperoxy benzoic acid.
U.S. Pat. No. 6,569,286 and published PCT No. WO0019006 (App. No. WO1999 GB03178) relate to a process for bleaching of wood and non-wood pulp. In this process an agglomerate containing, among others, a bleach activator (e.g., tetraacetylethylenediamine, TAED) and a peroxide soluble binder (e.g., polyvinyl alcohol) is added to a dilute solution of hydrogen peroxide. The components are allowed to react and the pH of the resulting mixture is chemically adjusted to a suitable alkaline pH and the pulp is contacted with the resulting solution. The patent notes the use of an ion-selective barrier or membrane between the anodic and cathodic chambers of the electrolysis unit of FIG. 1 therein. The barrier between the anodic and cathodic chambers in the device of FIG. 1 is described as “a cation exchange membrane, which permits migration of protons (H+) between the two chambers,” and as a separation between electrolytes in the two chambers.
The above processes differ from the processes provided herein, at least in part, in that they are all based on mixing chemical precursors with no electrochemical production or electrochemical pH adjustment components.
Peracids can be produced in electrochemical cells or reactors by establishing a potential difference across electrodes immersed in electrically-conducting fluid and introducing appropriate reactant materials. For example, U.S. Pat. No. 6,387,238 (Merk et al.) (corresponding to WO 01/10215 or JP-T-2003-506120) relates to a method for preparing an antimicrobial solution containing peracetic acid in which hydrogen peroxide or peroxide ions are formed electrolytically and the hydrogen peroxide or peroxide ions are then reacted with an acetyl donor to form peracetic acid.
U.S. Pat. No. 6,949,178 (Tennakoon et al.) discloses a process and apparatus for the preparation of peroxyacetic acid at the cathode of an electrolytic cell having an ionically conducting membrane in intimate contact between an anode and a gas diffusion cathode. The method comprises supplying an aqueous organic acid solution to the anode, supplying a source of oxygen to the cathode, and generating peroxyacid at the cathode.
European Patent EP1469102 (Ohsaka et al.) relates to a process and apparatus for electrolytically producing peracetic acid from acetic acid or acetate and an oxygen-containing gas using an electrolytic cell incorporating a gas diffusion electrode in the presence of a solid acid catalyst.
U.S. provisional application 61/019,825, filed Jan. 8, 2008 and U.S. application Ser. No. 12/350,866, filed Jan. 8, 2009 relate to frozen non-equilibrium peroxycarboxylic acid compositions useful as antimicrobial ice.